planner: fix can't find proper physical plan caused by virtual column

executor/tiflashtest/tiflash_test.go

@@ -1266,6 +1266,33 @@ func TestGroupStreamAggOnTiFlash(t *testing.T) {
  }
 }
 
+// TestIssue41014 test issue that can't find proper physical plan
+func TestIssue41014(t *testing.T) {
+ store := testkit.CreateMockStore(t, withMockTiFlash(2))
+ tk := testkit.NewTestKit(t, store)
+ tk.MustExec("use test;")
+ tk.MustExec("CREATE TABLE `tai1` (\n `aid` int(11) DEFAULT NULL,\n `rid` int(11) DEFAULT NULL\n) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin")
+ tk.MustExec("CREATE TABLE `tai2` (\n `rid` int(11) DEFAULT NULL,\n `prilan` varchar(20) DEFAULT NULL\n) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin")
+ tk.MustExec("alter table tai1 set tiflash replica 1")
+ tk.MustExec("alter table tai2 set tiflash replica 1")
+ tk.MustExec("alter table tai2 add index idx((lower(prilan)));")
+ tk.MustExec("set @@tidb_opt_distinct_agg_push_down = 1;")
+
+ tk.MustQuery("explain select count(distinct tai1.aid) as cb from tai1 inner join tai2 on tai1.rid = tai2.rid where lower(prilan) LIKE LOWER('%python%');").Check(
+ testkit.Rows("HashAgg_11 1.00 root funcs:count(distinct test.tai1.aid)->Column#8",
+ "└─HashJoin_15 9990.00 root inner join, equal:[eq(test.tai2.rid, test.tai1.rid)]",
+ " ├─Selection_20(Build) 8000.00 root like(lower(test.tai2.prilan), \"%python%\", 92)",
+ " │ └─Projection_19 10000.00 root test.tai2.rid, lower(test.tai2.prilan)",
+ " │ └─TableReader_18 9990.00 root data:Selection_17",
+ " │ └─Selection_17 9990.00 cop[tikv] not(isnull(test.tai2.rid))",
+ " │ └─TableFullScan_16 10000.00 cop[tikv] table:tai2 keep order:false, stats:pseudo",
+ " └─TableReader_23(Probe) 9990.00 root data:Selection_22",
+ " └─Selection_22 9990.00 cop[tikv] not(isnull(test.tai1.rid))",
+ " └─TableFullScan_21 10000.00 cop[tikv] table:tai1 keep order:false, stats:pseudo"))
+ tk.MustQuery("select count(distinct tai1.aid) as cb from tai1 inner join tai2 on tai1.rid = tai2.rid where lower(prilan) LIKE LOWER('%python%');").Check(
+ testkit.Rows("0"))
+}
+
 func TestTiflashEmptyDynamicPruneResult(t *testing.T) {
  store := testkit.CreateMockStore(t, withMockTiFlash(2))
  tk := testkit.NewTestKit(t, store)

planner/core/exhaust_physical_plans.go

@@ -2701,6 +2701,10 @@ func (la *LogicalAggregation) getStreamAggs(prop *property.PhysicalProperty) []P
  // TODO: remove AllowDistinctAggPushDown after the cost estimation of distinct pushdown is implemented.
  // If AllowDistinctAggPushDown is set to true, we should not consider RootTask.
  if !la.ctx.GetSessionVars().AllowDistinctAggPushDown {
+ // if variable doesn't allow DistinctAggPushDown, just produce root task type.
+ taskTypes = []property.TaskType{property.RootTaskType}
+ } else if !la.canPushToCop(kv.TiKV) {
+ // if variable does allow DistinctAggPushDown, but OP itself can't be pushed down to tikv, just produce root task type.
  taskTypes = []property.TaskType{property.RootTaskType}
  } else if !la.distinctArgsMeetsProperty() {
  continue
@@ -2852,6 +2856,15 @@ func (la *LogicalAggregation) tryToGetMppHashAggs(prop *property.PhysicalPropert
  return
 }
 
+// getHashAggs will generate some kinds of taskType here, which finally converted to different task plan.
+// when deciding whether to add a kind of taskType, there is a rule here. [Not is Not, Yes is not Sure]
+// eg: which means
+//
+// 1: when you find something here that block hashAgg to be pushed down to XXX, just skip adding the XXXTaskType.
+// 2: when you find nothing here to block hashAgg to be pushed down to XXX, just add the XXXTaskType here.
+// for 2, the final result for this physical operator enumeration is chosen or rejected is according to more factors later (hint/variable/partition/virtual-col/cost)
+//
+// That is to say, the non-complete positive judgement of canPushDownToMPP/canPushDownToTiFlash/canPushDownToTiKV is not that for sure here.
 func (la *LogicalAggregation) getHashAggs(prop *property.PhysicalProperty) []PhysicalPlan {
  if !prop.IsSortItemEmpty() {
  return nil
@@ -2866,6 +2879,10 @@ func (la *LogicalAggregation) getHashAggs(prop *property.PhysicalProperty) []Phy
  if la.HasDistinct() {
  // TODO: remove after the cost estimation of distinct pushdown is implemented.
  if !la.ctx.GetSessionVars().AllowDistinctAggPushDown {
+ // if variable doesn't allow DistinctAggPushDown, just produce root task type.
+ taskTypes = []property.TaskType{property.RootTaskType}
+ } else if !la.canPushToCop(kv.TiKV) {
+ // if variable does allow DistinctAggPushDown, but OP itself can't be pushed down to tikv, just produce root task type.
  taskTypes = []property.TaskType{property.RootTaskType}
  }
  } else if !la.aggHints.preferAggToCop {